1. Field of the Invention
The present invention relates to a pipe connecting structure to mutually join pipes.
2. Description of the Prior Art
There are known various methods of joining pipes mutually. For example, steel pipes are mutually connected by employing a screwed joint method, a flange joint method, a welded joint method, and so forth.
In the screwed joint method, pipe ends of both of pipes to be connected are machined by a thread cutting device so as to form external threads, and seal material (a joint seal or the like) is applied to the external threads. Thereafter, the external threads are screwed into a coupling having internal threads, thereby mutually joining the pipes. The method is chiefly effective in mutually connecting steel pipes having small diameters.
In the flange joint method, as in the case of the screwed joint method, the pipe ends of both the pipes to be connected are machined to form the external threads, and the external threads of the pipes are respectively screwed into flanges having an internal thread. Further, a packing is interposed between the flanges, and the flanges are mutually clamped by a bolt and a nut, thereby mutually joining the pipes. The method is chiefly effective in mutually connecting steel pipes having large diameters.
In the welded joint method, edge preparation is applied by a beveling machine to the pipe ends of both the pipes to be connected, and brazing material is temporarily tacked into a V-shaped groove defined by the mutually butted pipe ends. Further, after centering, an electric welder is used to melt the brazing material so as to join the pipes forming the V-shaped groove. The method is chiefly effective in mutually connecting the steel pipes having the large diameters.
A brazing joint method is also employed to mutually connect the steel pipes. In the brazing joint method, sealant (flux) is applied to the steel pipe and a steel joint, and a pipe end is inserted into the joint which is preheated by a heater such as torch lamp. After preheating, steel pipe brazing material is poured into a gap between the pipe and the joint, thereby joining the pipes.
Alternatively, stainless pipes are mutually connected by employing a mechanical joint method, or the welded joint method. In the mechanical joint method, a diameter of a pipe end is extended or reduced by a dedicated jig, and a packing formed according to a shape of the pipe end is mounted to the extended or reduced pipe end, thereafter clamping by a threaded cap nut. The method is effective in mutually connecting stainless pipes having small diameters. As in the case of the steel pipes, the welded joint method is carried out by using stainless pipe brazing material and a dedicated welding machine. The method is effective in mutually connecting stainless pipes having large diameters.
As set forth above, one of various joint methods is conventionally employed according to material or a diameter of a tube. Thus, there are such problems that these various methods require dedicated machines, dedicated jigs, tools and so forth, and operation requires a skilled operator. Further, it is difficult to ensure a sufficient pressure resistant and water resistant performance by a simple operation.